Only in Latin. (Recruitment)

by Funkmon , Wednesday, November 15, 2017, 18:03 (2663 days ago) @ Cody Miller

The copula links the complement to the subject. In Latin, whence this English rule came a couple hundred years ago. Now, in Old English, we DID mark this with a nominative case. Case markings are essentially gone, however, and nobody did this for a long time. Nobody continues to do this. Disjunctive pronouns are accusative in the past 800 years of English and are treated as objects, and I think also were in Vulgar Latin. They are in French iirc.

It's currently an idiomatic usage in people who know the "rule," who say things like your father. We know it's idiomatic as it doesn't show up except in certain phrases, like "this is he" or "this is I."

Your father wouldn't say of your mom's picture, "this is she in 1971," he would say "this was her in 1971," more than likely.

Were he to have completely internalized that rule, which I highly doubt but is not out of the realm of possibility, he is very steadfast in his choices, and I would say non standard in all but idiomatic usage, like what you say he does on the phone.